Canning 101: How to Ensure That Your Jam Sets

One of the trickiest things about making jam is achieving the set sweet spot. Cook it too long and you worry about the integrity of your cutlery as you reach in for a spoonful. Cut the stove time short and when it comes time to eat, the jam threatens to run off your toast in sticky rivulets (do know that jam this consistency is still amazing on pancakes or in yogurt. Call it a rustic syrup or old fashioned preserves and your friends will still be wowed).

First off, know that even the most experience jam maker has an off day here and there. The same recipe can yield a perfect set on Saturday and make an unfortunately sloshy batch on Sunday. Jam is influenced by the width of the pot you use to cook it, the ratio of sugar to water in the fruit, the amount of pectin in the fruit (as well as whether you add additional pectin), the elevation at which you’re cooking and even the amount of humidity in the air.

Here are a few things to keep in mind as you prepare to make a batch of jam…

As I mentioned above, the width of your pot can influence the set of your jam. Always choose the widest pot you have at your disposal that also has enough height to let the jam boil vigorously. More surface area means faster evaporation and ample height means you can crank the heat and let it boil. Getting the water evaporated out of your cooking jam at a speedy clip is integral to having a nice, spreadably sticky jam.

Take the jam’s temperature. Jam making is much like candy making in that you’re applying enough heat to the fruit and sugar to raise the temperature over the boiling point of 212 degrees and alter the structure of the sugar. The jam reaches its ideal set point at 220 degrees, so keep careful watch. Know that if you reduce the amount of sugar in your recipe too drastically, you may not be able to get your cooking jam up to the set point.

Before you take the jam off the heat, try the plate test. At the beginning of cooking (or even before) stash a couple saucers or sandwich plates in your freezer. When you believe the jam is cooked, grab one of the plates and plop a small spoonful at the center. Let it sit for a minute or two and then gently prod the puddle of jam with your finger. If it’s formed a surface skin and seems to be developing a certain solidity, it is done. If it is runny and saucy, give it a few more minutes.

Another test is the sheet test. Here, you stir a spoon through your jam and the remove it from the pot. Holding it over the cooking jam, watch as the remnants on the spoon drip back down. Do they fall back in runny drips, like rain on a window? If so, it’s not quite done. However, if they seem thick and run together in more of a sheet, your jam is finished.

Cooking times are estimates. When the recipe gives an amount of time for you to let the jam cook, know that that is only an approximate time. The recipe writer doesn’t know how hot your stove cooks, whether you’re in arid New Mexico verses sticky Philadelphia or what size pot you’re cooking the jam in. Use your judgment.

Additional pectin can help improve set, but it isn’t always a panacea. I’ve had jams that included additional pectin end up runny and then made others with no additional pectin that have firmed right up. Additionally, I’ve found recently that my beloved Certo liquid pectin isn’t working as well this year as it did in years past. I don’t know if they’ve changed the formula, but it’s thrown me off and made me remind myself of the basics of set all over again.

96 Responses to Canning 101: How to Ensure That Your Jam Sets

[…] and cook until it is reduced by more than half, reads 220 degrees F on a thermometer and passes the plate/sauce/wrinkle test. When it is finished cooking, pour marmalade into prepared jars. Wipe rims, apply lids and rings […]

I used Certo premium liquid fruit pectin. This was my first attempt and it failed miserably. I have a very runny syrup. I am thinking that I may have put too much Certo in and under sugared. I always cut sugar because I prefer healthier. Unfortunately, I read right on the box (after I was supposedly finished) that exact amounts of sugar are crucial. So, I went back to the stove and poured the remainder of my organic sugar and let it cook for a couple of minutes. Again, not knowing really what I was doing. How do I save this beautiful chunky syrup? Maybe corn starch and blending it a bit? Thoughts?

So, being a total newbie to jam making, I do wish someone had mentioned that it is possible to burn jam. I was watching my temps quite avidly and it just did not seem to want to get to 220 and them all of a sudden was at 225 and I smelled burning. Am pretty perturbed, but I guess I will at least know for next time. Maybe something to warn others of?

[…] making your own jam you will never buy it from the grocery store again. Check out Food in Jars, foodinjars.com/2010/07/canning-101-how-to-ensure-that-your-jam-sets/, it has a wonderful posting on how to make great jam every time. Homemade jam is also a wonderful […]

[…] boil and let cook for 25-30 minutes, skimming off any foam that appears. After 25 minutes, start testing the jam to see if it’s set. (I use the plate-in-the-freezer method.) I did not process this in a water-bath to be shelf […]

[…] to a boil and cook for 15-20 minutes, stirring frequently, until the jam thickens and passes the plate test. Ladle into sterilized jars. Put on lids and rings. Process the jars in a boiling water bath for 15 […]

[…] cannot be stirred down, add the pectin and boil hard, stirring constantly for one minute. (Check jam consistency at this point. Add more pectin/ cook more if needed.) Remove from the heat and skim off the foam. […]

If I am making a jam and the recipe calls for 1-3/4 oz. powdered fruit pectin, can I substitute the Certo liquid pectin and if so, how much do I use. I believe it comes in 3 oz pkg. Any help would be appreciated.

[…] by half and reaches at least 220 degrees on the thermometer. (Mine cooked 25-30 minutes). Use the plate test to check and make sure it will set. (Super short version: put a drop of boiling hot marmalade on a […]

[…] to bubble more rapidly, about 10 mins. Add the ginger and continue to cook until the jam is set: this information from Food in Jars is very helpful in determining set point, if you have questions. I have made this jam a dozen […]

[…] or need to fix a runny batch, these articles from Food in Jars really helped me save my batches: How to Ensure That Your Jam Sets and How to Save Runny Jam. I’ll be experimenting with this in the future and hope I’m […]

[…] In a small bowl, whisk sugar and pectin until well incorporated. Add sugar-pectin blend to violet water and whisk until completely dissolved. Turn heat up to medium high and bring mixture to a boil, stirring occasionally. You want to stay close to the pot because it does have a tendency to bubble over if left unattended. Continue cooking until mixture has thickened slightly, about 5-10 minutes, skimming off any foam as you go (there will be a lot). Jelly is ready when it passes the chilled plate test. […]

[…] or need to fix a runny batch, these articles from food in jars really helped me save my batches: how to ensure that your jam sets and how to save runny jam. i’ll be experimenting with this in the future and hope i’m […]

[…] For me, canning season really won’t begin in earnest until July, maybe August (beans, tomatoes, beets — I can’t wait!) but in the spring, I ease into the routine with a few small batches of things. I started out with a round of rhubarb jam. I think next to plum, it’s my favorite jam and it thickens really easily without the use of commercial pectin or the addition of high-pectin fruits. My first few attempts at this jam actually produced more of a paste which while delicious, was a bit of a challenge to eat. That was in my early canning days, before I knew about the frozen plate trick. Do you know about that? You should. Check it out. […]

[…] a delicious jamlike consistency. Don’t just take it from me, check out this great post from Food in Jars. So put a candy thermometer in your jam, keep stirring every few minutes to make sure it’s […]

i have made jelly, and this batch is runny, new season, i dont want runny jelly. i see that meny things can make it thin and runny, i am about to start jelly, i have heard a wooden spoon is a must, is this true, also adding a teaspoon of butter will help make it a dark color , lets get to the point, how do i make normal jelly not to thin, and runny

[…] a knife. Make certain your marmalade reaches 220 degrees during the boiling process, and passes the plate/saucer/wrinkle test. Mine turned out a wee bit runny, but has been absolutely delicious on scones, and as a topping for […]

Thanks so much for the info about the 220 degree set point! I had runny jam, so I put it back in the pot with just a tablespoon of extra pectin, and brought it to the 220 degrees. It set perfectly! The next batch I made, no extra pectin, but brought it to 220 degrees and it is PERFECT! Obviously my cook time was much shorter than needed to make the jam!! Thanks again!!

[…] How to Ensure That Your Jam Sets – There are so many variables in jam making. Read through this post to understand all the factors and save yourself the disappointment of runny jam (though truly, even runny jam is delicious). […]

[…] Cook the mixture over medium heat, stirring frequently, until you reach at least 210 degrees and as high as 220. The mixture should be thicker than when you started, more like jam. If not, refer to troubleshooting tips. […]

[…] frequently, until the tomatoes have softened and the syrup has gotten thick. Check set with plate test. Once you’re satisfied with the set, remove the pot from the heat and stir in lemon zest and […]

[…] and cook until it is reduced by more than half, reads 220 degrees F on a thermometer and passes the plate/sauce/wrinkle test. When it is finished cooking, pour marmalade into prepared jars. Wipe rims, apply lids and rings […]

[…] making your own jam you will never buy it from the grocery store again. Check out Food in Jars, foodinjars.com/2010/07/canning-101-how-to-ensure-that-your-jam-sets/, it has a wonderful posting on how to make great jam every time. Homemade jam is also a wonderful […]

[…] boil and let cook for 25-30 minutes, skimming off any foam that appears. After 25 minutes, start testing the jam to see if it’s set. (I use the plate-in-the-freezer method.) I did not process this in a water-bath to be shelf […]

[…] to a boil and cook for 15-20 minutes, stirring frequently, until the jam thickens and passes the plate test. Ladle into sterilized jars. Put on lids and rings. Process the jars in a boiling water bath for 15 […]

[…] cannot be stirred down, add the pectin and boil hard, stirring constantly for one minute. (Check jam consistency at this point. Add more pectin/ cook more if needed.) Remove from the heat and skim off the foam. […]

[…] by half and reaches at least 220 degrees on the thermometer. (Mine cooked 25-30 minutes). Use the plate test to check and make sure it will set. (Super short version: put a drop of boiling hot marmalade on a […]

[…] to bubble more rapidly, about 10 mins. Add the ginger and continue to cook until the jam is set: this information from Food in Jars is very helpful in determining set point, if you have questions. I have made this jam a dozen […]

[…] or need to fix a runny batch, these articles from Food in Jars really helped me save my batches: How to Ensure That Your Jam Sets and How to Save Runny Jam. I’ll be experimenting with this in the future and hope I’m […]

[…] In a small bowl, whisk sugar and pectin until well incorporated. Add sugar-pectin blend to violet water and whisk until completely dissolved. Turn heat up to medium high and bring mixture to a boil, stirring occasionally. You want to stay close to the pot because it does have a tendency to bubble over if left unattended. Continue cooking until mixture has thickened slightly, about 5-10 minutes, skimming off any foam as you go (there will be a lot). Jelly is ready when it passes the chilled plate test. […]

[…] or need to fix a runny batch, these articles from food in jars really helped me save my batches: how to ensure that your jam sets and how to save runny jam. i’ll be experimenting with this in the future and hope i’m […]

[…] For me, canning season really won’t begin in earnest until July, maybe August (beans, tomatoes, beets — I can’t wait!) but in the spring, I ease into the routine with a few small batches of things. I started out with a round of rhubarb jam. I think next to plum, it’s my favorite jam and it thickens really easily without the use of commercial pectin or the addition of high-pectin fruits. My first few attempts at this jam actually produced more of a paste which while delicious, was a bit of a challenge to eat. That was in my early canning days, before I knew about the frozen plate trick. Do you know about that? You should. Check it out. […]

[…] a delicious jamlike consistency. Don’t just take it from me, check out this great post from Food in Jars. So put a candy thermometer in your jam, keep stirring every few minutes to make sure it’s […]

[…] a knife. Make certain your marmalade reaches 220 degrees during the boiling process, and passes the plate/saucer/wrinkle test. Mine turned out a wee bit runny, but has been absolutely delicious on scones, and as a topping for […]